Friday, December 10, 2004

After combing the scientific literature, researchers conclude head hair and fur aren't the same

Mammals have fur over most of their bodies, but at some point during evolution, we humans lost that fur covering. Researchers at Washington University School of Medicine in St. Louis argue that hair on the head is somehow different from fur because fur stops growing when it reaches a certain length, but our head hair continues to grow. To drive home their argument, they ask in a recent article in the journal Evolutionary Anthropology, "Have you ever seen a chimpanzee getting a haircut?"

When Arthur H. Neufeld, Ph.D., the Bernard Becker Professor of Ophthalmology and Visual Sciences at Washington University School of Medicine in St. Louis, first put forth his idea that human head hair is somehow different from fur, over dinner with his close friend and colleague Glenn C. Conroy, Ph.D., professor of anatomy and anthropology, Conroy told him he wasn't aware of anyone in anthropology studying differences between hair and fur.

"So we talked about it for a while and asked questions like why does human head hair continue to grow? Where did this difference arise in the evolutionary process?" Neufeld recalls. "And the more we looked at it, the more we found that there really isn't anything in the literature."

One reason might be that under a microscope a hair follicle taken from the leg would look just about the same as one from the head. Our human "fur" if you will — the hair under the arms, on the legs and elsewhere — is anatomically identical to head hair.

Experiments related to hair transplantation, however, have demonstrated that where hair comes from is important in how it grows. Hair transplants always move hair from one part of the head to another because the procedure doesn't work if hair is moved onto the head from another part of the body. Nor does hair behave correctly when transplanted from the head to other parts of the body.

"When researchers transplanted hair from the head to the leg, it kept growing," Neufeld says. "It didn't grow as long as it would on the head, but the hair grew much longer than typical leg hair."